A new electrochemical sensor to determine Sunset yellow (SY) in foods has been developed. A composite consisting of highly dispersed polypyrrole (ppy) and single-walled carbon nanotube (ppy–SCNT) was synthesized as a modification via a facile method at room temperature. The ppy–SCNT composites were demonstrated to be highly sensitive for SY detection. The influences of pH value, amount of ppy–SCNT dispersion, accumulation time and scan rate on the signal enhancement of SY are discussed. Under optimal experimental conditions, the ppy–SCNT modified glass carbon electrode (ppy–SCNT/GCE) exhibited a wide linear response to SY ranging from 2.0 × 10−9 to 1.5 × 10−6 M with a high sensitivity of 91.53 μA μM−1 and a low detection limit of 3.0 × 10−10 M (S/N = 3). The novel ppy can prevent the aggregation of SCNT via π–π interaction, and enhance their electrochemical properties for the measurement of Sunset yellow in food samples. The novel sensor possesses following features: facile fabrication, easy operation and acceptable stability. The analysis of real sample drinks demonstrated that the electrode has excellent selectivity.
